56 ELECTRICAL GYMNOTE. 



have an outer and an inner edge. The outer is at- 

 tached to the skin of the animal, to the lateral muscles 

 of the fin, and to the membrane which divides the 

 great organ from the small ; and the whole of their 

 inner edges are fixed to the middle partition for- 

 merly described, as also to the air-bladder ; and 

 three or four terminate on that surface which in- 

 closes the muscles of the back. These septa are at 

 the greatest distance from one another at their ex- 

 terior edges near the skin, to which they are united; 

 and as they pass from the skin towards their inner 

 attachments, they approach one .another. Some- 

 times we find tw T o uniting into one. On that side 

 next to the muscles of the back they are hollow 

 from edge to edge, answering to the shape of those 

 muscles ; but become less and less so towards the 

 middle of the organ ; and from that, towards the 

 lower part of the organ, they become curved in 

 another direction. At the anterior part of the 

 large organ, where it is nearly of an equal breadth, 

 they run pretty parallel to one another, and also 

 pretty strait ; but where the organ becomes nar- 

 rower, it may be observed that two join pr unite 

 into one ; especially where a nerve passes across. 

 The termination of this organ at the tail is so very 

 small that I could not determine whether it con- 

 sisted of one septum or more. The distances be- 

 tween these septa will differ in fish of different sizes. 

 In a fish of two feet four inches in length I found 

 them one twenty-seventh of an inch distant from 

 one another ; and the breadth of the whole organ, 

 at the broadest part, about an inch and a quarter^ 



